The present invention relates to automatic irrigation sprinkler systems and more particularly to controllers having timekeeping capability for starting and stopping the stations of the sprinkler system on a periodic basis.
Watering of large areas such as golf courses, parks, and the like is a complicated matter. Typically, it is accomplished by automatic equipment. Such automatic irrigation sprinkler systems have a plurality of sprinkler stations strategically located throughout the area to be irrigated. Each sprinkler station contains a valve for controlling the flow of water entering the station from a source of pressurized water and exiting the station to a sprinkler line terminating in a plurality of sprinkler heads located at preselected locations so as to water the lawns, trees, and shrubbery in a thorough manner. The various sprinkler stations are electrically connected back to a common controller. The water required by lawns, trees, and shrubbery differs. The amount of watering required to maintain a lawn may, in fact, be detrimental to certain trees and shrubs. Thus, it is usual to operate the sprinklers associated with lawn areas from one sprinkler station and those associated with shrubberies and trees from a separate and distinct station. The controller to which the sprinkler stations are all ultimately connected is a clock operated device with the capability of keeping track of both the hours of the day and the day of the week. The clock mechanisms contained therein operate switches which open and close the circuits to the various sprinkler stations so as to accomplish the irrigation of the area in an optimum manner.
In prior art irrigation sprinkler system controllers, these functions have been accomplished in a mechanical manner. That is, mechanical clock mechanisms drive one or more controller wheels having pins, cams, etc. mounted thereon which operate the sprinkler station switches. The controller wheels of such apparatus are typically marked with the parameter being controlled such as the time of day or day of the week. The activation pins, cams, etc. are movable by the operator so as to "program" the controller to operate in the desired manner.
With only a few sprinkler stations to be controlled and under steady conditions, such apparatus is fairly workable for its intended purpose. As the number of stations to be controlled becomes large, such as in the irrigation of golf courses and other large areas, mechanical controllers can become quite large. As with all mechanical devices, there is, of course, always the consideration of mechanical failures due to contact corrosion and limited duty cycles, as well as inoperation or changing of operating times or the like due to the movement of mechanical parts. More important, however, conditions for the optimum irrigation of large areas over extended periods of time are never static. Unseasonable weather, a sudden shower or drought condition, and many other factors can dictate changes in the irrigation schedule as being desirable. In complex multi-station mechanical controllers, such spontaneous reprogramming is often a difficult task. Difficult at least to the point of operators often bypassing a desirable slight modification of the sprinkling schedule as opposed to accomplishing it with mechanical means. For example, cancelling the balance of an irrigation day or requesting an additional watering period for one or more sprinkler stations is not a trivial task with the typical mechanical controller. Moreover, in the event of a power loss for a period of time, the clocks in such apparatus will become disoriented vis a vis real-time so that the sprinkling sequence will no longer be as desired. In such locations as golf courses, parks, etc. where public interface is an expected part of the daily routine, sprinkler operation must be accomplished at times and in locations so as to have minimal impact. In the event that the sprinkler sequence is modified due to a power failure, the sprinklers may end up in undesirable operation simultaneously with a time of maximum public usage of the facility.
Wherefore, it is the object of the present invention to provide a solid state controller for automatic irrigation sprinkler systems which is compact, easily reprogramable for both extended and one time operation and which includes a battery backup system for maintaining the real-time clock in synchronization with real time even in the event of main controller power failure.